Although cruise control mechanisms have been used in motor vehicles for many years, practical applications have, for the most part, been limited to the relatively simple task of keeping a vehicle at a substantially constant speed. In the past, prudent driving practice tended to limit use of cruise control to relatively open highway driving. Following in the track of another vehicle and maintaining a substantially constant or safe distance behind it are functions which have been far better performed under direct driver control. Proposals for mechanisms which would enable a constant or safe vehicle separation to be maintained automatically have tended to require that special apparatus be installed in both the followed and the following vehicle, thus severely limiting usefulness in normal traffic situations.
In recent years, a body of art has grown which uses video cameras and adaptive (i.e., interactive) digital processing techniques to control the mechanical positioning of work pieces in manufacturing processes. Art of this type is illustrated in U.S. Pat. No. 4,547,800, which issued Oct. 15, 1985, to the present inventor. In the arrangement shown in the cited patent, a sample work piece is first placed in a predetermined position and detected by an image sensor to provide reference image information which is stored in memory. Subsequently, a work piece under inspection is repetitively detected by the image sensor and new images are formed which are then subjected to either lateral movement or rotation or both until correlation apparatus detects a substantial match between a transformed image and the reference image stored in memory. The resulting information is then used to position the work piece accurately for processing.
Because the automatic work piece positioning art which has developed for the manufacturing environment tends to deal only with the alignment of objects within a single plane, it tends not to be particularly helpful when one attempts to deal with the motor vehicle cruise control problem. Motor vehicles in traffic are continually changing positions with respect to one another in both distance and directional bearing. A need remains, therefore, for motor vehicle cruise control which can employ adaptive techniques to control either the distance of a following vehicle behind a followed vehicle or the directional bearing of a following vehicle from a followed vehicle or both.